The present invention relates to turbochargers. In particular, the invention provides increased turbocharger efficiency by reducing turbulence caused by the flow of wastegate discharge gases as those gases enter the primary turbine discharge flow stream of the turbocharger.
Prior art turbochargers typically utilize a wastegate to limit the amount of energy imparted to the turbine by exhaust gases. The wastegate gases bypass the turbine blades in the primary volute and then re-enter the primary turbine discharge flow stream. A significant problem with the prior art is that the wastegate gas flow stream contacts the primary turbine flow stream at right angles, causing turbulence and reducing the overall turbocharger efficiency.
The turbocharger design of the present invention provides a 360° directional matching flow of wastegate discharge gases to the primary turbine discharge flow stream. The two flow streams are moving in parallel, circular paths when they join. The present invention provides, for the first time, a secondary volute for wastegate gases. The secondary volute is designed to match the wastegate flow stream to the primary discharge flow stream. This novel design greatly reduces turbulence and improves turbine efficiency which in turn has significant commercial value in at least two significant respects described below.
A first and primary object of the present invention is to achieve a lower exhaust back pressure between the turbocharger and the engine, thereby improving engine operating efficiency. Improved operating efficiency directly translates into improved fuel economy and power.
A second object of our new turbocharger design is to significantly improve the flow distribution of exhaust gases to the catalytic converter. By equalizing the flow distribution across the exhaust flow stream, our invention provides either an increased catalytic converter life or reduction of the size of the catalytic converter utilized for a given engine, or both. Automotive manufacturers can therefore either extend the service life of the catalytic converter to meet steadily increasing emission standards or they can reduce the cost of the catalytic converter by reducing its size.
Further objects and advantages will become apparent from the following description and drawings.